Window with UV-treated low-E coating and method of making same

ABSTRACT

A coated article includes a low-emissivity (low-E) coating supported by a substrate (e.g., glass substrate) for use in a window, where the low-E coating is exposed to ultraviolet (UV) radiation in order to improve the coating&#39;s and thus the coated article&#39;s electrical, optical and/or thermal blocking properties. Exposing the low-E coating to UV radiation, e.g., emitted from a UV lamp(s) and/or UV laser(s), allows for selective heating of a contact/seed layer which transfers energy to the adjacent IR reflecting layer.

Certain embodiments of this invention relate to a coated articleincluding a low-emissivity (low-E) coating for use in a window, wherethe low-E coating is intentionally exposed to intense ultraviolet (UV)radiation in order to improve the coating's and thus the coatedarticle's electrical, optical and/or thermal blocking properties. Thelow-E coating includes at least one infrared (IR) reflecting layercomprising or consisting essentially of silver, where the silverinclusive layer is located on (e.g., grown on by sputtering) anddirectly contacting a contact/seed layer comprising or consistingessentially of a material such as zinc oxide and/or zinc stannate. TheIR reflecting layer and contact/seed layer may be located betweendielectric layers in the low-F coating. Exposing the low-E coating to UVradiation, e.g., emitted from a UV lamp(s) and/or UV laser(s), allowsfor selective heating of the contact/seed layer (e.g., of zinc oxideand/or zinc stannate) which in turn transfers the heat energy to theadjacent IR reflecting layer of or including silver. This heating of thesilver inclusive layer improves the silver layer's electrical, opticaland/or thermal blocking properties. For example, this heating of thesilver based layer caused by exposing the low-E coating to the UVradiation increases the silver based layer's conductivity (lowers itsresistance) which in turn increases its ability to block (e.g., reflect)undesirable IR radiation. As another example, this heating of the silverbased layer caused by low-E coating's exposure to the UV radiationincreases the visible transmission of the silver based layer therebyimproving its optical properties. The UV treated coated article, withits improved electrical, thermal blocking, and/or optical properties,may be used in the context of monolithic or insulating glass (IG) windowunits such as architectural windows for office buildings and/orapartment buildings, windows for homes, windows for freezer doors,and/or vehicle windows.

BACKGROUND OF THE INVENTION

IG window units are known in the art. For example, see U.S. Pat. Nos.6,632,491, 6,014,872; 5,800,933; 5,784,853; 5,557,462; 5,514,476;5,308,662; 5,306,547; and 5,156,894, all of which are herebyincorporated herein by reference. An IG window unit typically includesat least first and second substrates spaced apart from one another by atleast one spacer and/or seal. The gap or space between the spaced apartsubstrates may or may not be filled with a gas (e.g., argon) and/orevacuated to a pressure less than atmospheric pressure in differentinstances. Solar control coatings, such as low-E coatings, are sometimesused in connection with IG window units in order to block IR rays fromreaching the interior of a building on which the IG window unit islocated.

Sputter deposited thin film solar control (e.g., low-E) coatings onglass are known in the art. For example, see U.S. Pat. Nos. 8,173,263,8,142,622, 8,124,237, 8,101,278, 8,017,243, 7,998,320, 7,964,284,7,897,260, 7,879,448, 7,858,191, 7,267,879, 6,576,349, 7,217,461,7,153,579, 5,800,933, 5,837,108, 5,557,462, 6,014,872, 5,514,476,5,935,702, 4,965,121, 5,563,734, 6,030,671, 4,898,790, 5,902,505,3,682,528, all of which are hereby incorporated herein by reference.Sputter deposition of low-E coatings at approximately room temperature,not using an intentionally heated substrate, is advantageous due to thelower cost of non-heated vacuum coaters, high deposition rate, energysaving during deposition, and lower maintenance.

A sputter-deposited low-E coating usually includes a number of layers,including a silver layer that is deposited directly on a contact/seedlayer of a material such as zinc oxide or zinc stannate (ZnSnO_(x)). Thesilver has transmission in the visible range at appropriate thicknessesand reflection in the IR range of the spectrum. Deposition conditions ofthe contact/seed layer and layer(s) over the silver determine opticaland electrical properties of the silver such as solar heat gaincoefficient, emissivity, sheet resistance, and visible transmission. Thequality of room temperature sputter-deposited thin silver layers ispoor, and heat treatment is often requires to improve the optical andelectrical properties of the silver to acceptable levels. Such heattreatment (HT) is typically done in a convection oven, e.g., performedin combination with glass tempering for temperable products. However,there are also non-temperable and non-tempered products which do nothave the advantage of having had the silver subjected to the HT duringthe tempering process.

It would be desirable to be able to improve the quality ofsputter-deposited silver layers, e.g., in the context of low-E coatings,without having to subject the coated article including the coating to athermal tempering process. Attempts to improve the quality of the roomtemperature sputter-deposited silver in low-E coatings by IR irradiationhave proven problematic because much of the IR radiation if exposed fromthe coating side of the glass gets reflected by the silver, or ifexposed from the glass side of the coated article gets first absorbed bythe glass before reaching the coating and can damage the glass substratebefore the temperature elevates to levels sufficient for improving thesilver quality. It has been found, in accordance with certain exampleembodiments of this invention, that UV exposure is highly advantageouswith respect to improving the quality of sputter-deposited silverlayer(s), e.g., in the context of low-E coatings. For example, thecoated article (e.g., glass substrate with a low-e coating thereon) canbe exposed from the coating side so that the UV is absorbed by part(s)of the coating without damaging the glass substrate, and much of the UVis able to pass through the silver layer(s) without being reflectedbefore it can perform the desired heating by heating up other layer(s)which are capable of transferring heat to the silver in order to improveits optical and electrical and properties. Thus, in certain exampleembodiments of this invention, UV exposure of a low-E coating can beused to efficiently improve optical and/or electrical properties ofsilver based layer(s), and thus also improve such properties of theoverall coating, such as one or more of solar heat gain coefficient,emissivity, sheet resistance, and visible transmission.

BRIEF SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

Certain embodiments of this invention relates to a coated articleincluding a low-emissivity (low-E) coating for use in a window, wherethe low-E coating is intentionally exposed to intense ultraviolet (UV)radiation in order to improve the coating's and thus the coatedarticle's electrical, thermal blocking, and/or optical properties. Thelow-E coating may include at least one infrared (IR) reflecting layercomprising or consisting essentially of silver, where the silverinclusive layer is located on (e.g., grown on by sputtering) anddirectly contacting a contact/seed layer comprising or consistingessentially of a material such as zinc oxide and/or zinc stannate. TheIR reflecting layer and contact/seed layer may be located betweendielectrics in the low-E coating. Exposing the low-E coating to UVradiation, e.g., emitted from a UV lamp(s) and/or UV laser(s), allowsfor selective heating of the contact/seed layer(s) (e.g., of zinc oxideand/or zinc stannate) which in turn transfers the heat energy to theadjacent IR reflecting layer of or including silver. This heating of thesilver inclusive layer, by way of the heat generated by the contact/seedlayer's absorbing of the UV and resulting heat generation, improves thesilver layer's electrical, optical and/or thermal blocking properties.For example, this heating of the silver based layer caused by exposingthe low-E coating to the UV radiation increases the silver based layer'sconductivity (lowers its resistance) which in turn increases its abilityto block (e.g., reflect) undesirable IR radiation. As another example,this heating of the silver based layer caused by low-E coating'sexposure to the UV radiation increases the visible transmission of thesilver based layer thereby improving its optical properties. In certainexample embodiments, the entire or substantially the entire coating(with respect to its area as viewed from above) is exposed to the UVradiation, so that the entire or substantially the entire silver basedlayer is improved with respect to electrical, optical and/or thermalblocking properties. The bandgap of the contact/seed layer(s) is suchthat the contact/seed layer(s) absorbs more UV radiation than any otherlayer in the coating in certain example embodiments, and thus is themain layer(s) that generates heat. Intense UV exposure causes thecontact/seed layer and silver based layer to heat up in exposed areas.Heating of the contact/seed layer causes the adjacent silver layer toalso heat up in the UV exposed areas thereby physically changing thesilver layer in those areas so as to densify and cause the silver layerto become more conductive and more transparent to visible light in theexposed areas. The UV treatment may be performed after the entire low-Ecoating has been deposited on the substrate, and/or during or after thecontact/seed layer and the silver inclusive layer have been depositedbut before other overlying layers are deposited. The UV treated coatedarticle, with its improved electrical, optical and/or thermal blockingproperties, may be used in the context of monolithic or insulating glass(IG) window units such as architectural windows for office buildingsand/or apartment buildings, windows for homes, windows for freezerdoors, and/or vehicle windows.

In certain example embodiments, there is provided a method of making acoated article for use in a window, the method comprising: having acoated article including a substrate that supports a coating comprisingat least one layer comprising silver located on a layer comprising metaloxide that can absorb ultraviolet (UV) radiation; directing UV radiationfrom at least one UV source toward the coating and exposing the coatingto UV radiation in order to reduce a sheet resistance of the coatingand/or increase visible transmission of the coating.

In certain example embodiments of this invention, there is provided amethod of making a coated article for use in a window, the methodcomprising: having a coated article including a glass substrate thatsupports a coating (e.g., low-E coating) comprising at least onesubstantially metallic layer (e.g., Au or Ag based layer) locateddirectly on and contacting a layer comprising metal oxide that has abandgap of from 3.2 to 3.4 eV; directing UV radiation from at least oneUV source toward the coating and exposing the coating to UV radiation inorder to reduce a sheet resistance of the coating and increase visibletransmission of the coating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a technique used in making a coatedarticle for use in a window according to an example embodiment of thisinvention.

FIG. 2 is a partial cross sectional view of an insulating glass (IG)window unit made using at least the technique of FIG. 1.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like parts throughout the severalviews.

Referring to FIGS. 1-2, certain example embodiments of this inventionrelate to a coated article including a low-emissivity (low-E) coating 5on a substrate (e.g., glass substrate) 1 for use in a window, where thelow-E coating 5 is intentionally exposed to intense ultraviolet (UV)radiation 21 in order to improve the coating's and thus the coatedarticle's electrical, thermal blocking, and/or optical properties. Aradiation source(s) 20 may be used to expose the coating to UV radiationemitted therefrom. The radiation source(s) 20 may be an ultraviolet (UV)laser and/or lamp for emitting UV radiation 21 in certain exampleembodiments, such as a UV excimer or UV solid state laser. The low-Ecoating 5 may include at least one metallic and/or substantiallymetallic infrared (IR) reflecting layer 11 comprising or consistingessentially of silver, where the silver inclusive layer 11 is located on(e.g., grown on by sputtering) and directly contacting a contact/seedlayer 9 comprising or consisting essentially of a material such as zincoxide, tin oxide, and/or zinc stannate. The IR reflecting layer 11 andcontact/seed layer 9 may be located between dielectrics 7 and 15 in thelow-E coating. Exposing the low-E coating 5 to UV radiation 21, e.g.,emitted from a UV lamp(s) and/or UV laser(s) 20, allows for selectiveheating of the contact/seed layer(s) 9 (e.g., of zinc oxide, tin oxide,and/or zinc stannate) which in turn transfers the heat energy to theadjacent IR reflecting layer 11 of or including silver. This heating ofthe silver inclusive layer 11, by way of the heat generated by thecontact/seed layer's absorbing of the UV and resulting heat generation,improves the silver layer's electrical, optical and/or thermal blockingproperties. For example, this heating of the silver based layer 11caused by exposing the low-E coating 5 to the UV radiation 21 increasesthe silver based layer's conductivity (lowers its resistance) which inturn increases its ability to block (e.g., reflect) undesirable IRradiation. As another example, this heating of the silver based layer 11caused by low-E coating's exposure to the UV radiation 21 increases thevisible transmission of the silver based layer 11 thereby improving itsoptical properties. In certain example embodiments, the entire orsubstantially the entire coating (with respect to its area as viewedfrom above) is exposed to the UV radiation, so that the entire orsubstantially the entire silver based layer 11 is improved with respectto electrical, optical and/or thermal blocking properties. The bandgapof the contact/seed layer(s) 9 is such that the contact/seed layer(s) 9absorbs more UV radiation than any other layer (7, 11, 13, 15) in thecoating in certain example embodiments, and thus is the main layer(s)that generates heat. Intense UV exposure causes the contact/seed layer 9and silver based layer 11 to heat up in exposed areas. Heating of thecontact/seed layer 9 causes the adjacent silver layer 11 to also heat upin the UV exposed areas thereby physically changing the silver layer 11in those areas so as to densify and cause the silver layer 11 to becomemore conductive and more transparent to visible light in the exposedareas. Uses of UV radiation 21 from source(s) 20 allows selectiveheating of the contact/seed layer 9 (which may be a semiconductor), withsubsequent transfer of the heat energy to the adjacent silver basedlayer 11 (as opposed to IR irradiation which would largely be wasted onthe glass). Good choices for material of the seed/contact layer 9 arezinc oxide or zinc stannate semiconductors with bandgaps ranging fromabout 3.15 to 3.45, more preferably from about 3.2 to 3.4 eV, whichcauses the contact/seed layer 9 to absorb UV wavelengths shorter 364-387nm. For example, the emission line at 355 nm, common for excimer andsolid state UV lasers, is absorbed by such seed/contact layer materialsbut is poorly absorbed by glass 1 (only up to 15% of the 355 nm UVradiation is absorbed by glass) so that the glass is not significantlyheated thereby. The UV treatment may be performed after the entire low-Ecoating 5 has been deposited on the substrate, and/or during or afterthe contact/seed layer 9 and the silver inclusive layer 11 have beendeposited but before other overlying layers 13 and 15 are deposited. Theenergy used to improve the quality of the silver based layer 11 via UVexposure is a fraction of the energy required to cause essentially thesame changes while heating the coated article during a thermal temperingprocess in a conventional convection furnace where the majority ofenergy is wasted on heating the glass. It will be recognized that the UVexposure does not thermally temper the glass substrate 1 that supportsthe coating 5. Thus, glass substrate 1 is not thermally tempered incertain example embodiments of this invention.

The UV treated coated article, with its improved electrical, opticaland/or thermal blocking properties, may be used in the context ofmonolithic or insulating glass (IG) window units such as architecturalwindows for office buildings and/or apartment buildings, windows forhomes, windows for freezer doors, and/or vehicle windows. In IG windowunit embodiments (e.g., see FIG. 2), the IG window unit includes firstand second substrates (e.g., glass substrates) 1 and 3 spaced apart fromone another, wherein at least one of the substrates 1 supports UVtreated solar coating 5 such as a low-emissivity (low-E) coating. Inmonolithic window embodiments, a substrate (e.g., glass substrate) 1supports UV treated coating 5.

There are numerous advantages of improving silver quality via UVexposure, without having to heat the glass 1 supporting the coating 5 ina typical convection oven during thermal tempering. Heating of the glasssubstrate 1 (e.g., in a convection oven during thermal tempering) isassociated with the leaching out of certain diffusible elements from theglass such as sodium and potassium. When migrating to the glass surface,these elements can compromise the quality of the glass and/or coatingand contribute to corrosion in certain situations over long periods oftime. Thus, it is desirable to be able to heat the silver 11 via UV 21without having to significantly heat the glass substrate 1 that issupporting the coating 5. In this respect, the UV source(s) 20 may bepositioned on the same side of the glass substrate 1 that the coating 5is located, to further reduce heating of the glass as the seed/contactlayer 9 absorbs significant amounts of UV radiation before it reachesthe glass substrate 1. While it is possible that the glass 1 may bethermally tempered before and/or after UV exposure according to certainexample embodiments of this invention, it is pointed out that thermaltempering is not necessary to improve the quality of the silver due tothe UV exposure. Moreover, if the silver quality can be improved via UVwithout necessarily requiring thermal tempering, then both temperableand non-temperable low-E products can be made using essentially the samerecipe or layer stack; in such a case the improvement of silver qualityfor non-temperable products can be done via UV exposure discussed hereinwhile the improvement of silver quality for temperable products can bedone with via convectional tempering and/or via a combination ofnon-thermal (e.g., chemical) tempering and UV exposure discussed herein.Moreover, with UV exposure, improvement in silver quality can beachieved using a fraction of the energy compared to convectional heatingsuch as thermal tempering.

FIG. 1 is a cross sectional view of a technique used in making a windowaccording to an example embodiment of this invention. As shown in FIG.1, there is provided a coated article including a glass substrate 1 thatsupports a solar control coating 5. While substrate 1 is preferably ofglass, it could be of other material. Example solar management/controlcoatings (e.g., low-E coatings) 5 which may be provided on substrate 1are described in U.S. Pat. Nos. 8,173,263, 8,142,622, 8,124,237,8,101,278, 8,017,243, 7,998,320, 7,964,284, 7,897,260, 7,879,448,7,858,191, 7,267,879, 6,576,349, 7,217,461, 7,153,579, 5,800,933,5,837,108, 5,557,462, 6,014,872, 5,514,476, 5,935,702, 4,965,121,5,563,734, 6,030,671, 4,898,790, 5,902,505, 3,682,528, all of which arehereby incorporated herein by reference. In certain example embodiments,the solar management coating 5 may have an emissivity (E_(n)) of nogreater than 0.12, more preferably no greater than 0.10, and/or a sheetresistance (R_(s)) of no greater than 10 ohms/square, more preferably nogreater than 8 ohms/square. Of course, solar management coatings (e.g.,low-E coatings) 5 herein are not limited to these particular coatings,and any other suitable solar management coatings capable of blockingamounts of IR radiation may instead be used. Solar management coatings 5herein may be deposited on substrate 1 in any suitable manner, includingbut not limited to sputtering (e.g., at approximately room temperature),vapor deposition, and/or any other suitable technique.

A low-E coating typically includes at least one IR reflecting layer ofor including silver 11 sandwiched between at least a lower dielectric 7and an upper dielectric 15. The example low-E coating 5 in FIG. 1 mayinclude, for example, a lower dielectric layer(s) 7 of or includingtitanium oxide or silicon nitride, a lower contact/seed layer 9 of orincluding zinc oxide (e.g., ZnO), zinc aluminum oxide, zinc stannate(e.g., ZnSnO), tin oxide, and/or combinations thereof, IR reflectinglayer 11 of or including silver or gold, upper contact layer 13 of orincluding Ni and/or Cr (e.g., NiCr, NiCrO_(x), NiO_(x), or the like)that is located over and directly contacting the silver based layer 11,and upper dielectric layer(s) 15 of or including silicon nitride and/ortin oxide. The metal oxide based contact/seed layer 9 may optionally bedoped with material such as Al, Ni or Ti. In certain exampleembodiments, dielectric layer 15 may be made up of a lower layer of orincluding tin oxide and an upper layer of or including silicon nitrideand/or silicon oxynitride. Optionally, an overcoat of or includingzirconium oxide may be provided over dielectric layer 15. The layers ofthe thin film coating 5 may be deposited in any suitable manner, such asat approximately room temperature via sputtering. While the low-Ecoating 5 illustrated in FIG. 1 has only one IR reflecting layer 11 ofor including silver, it will be appreciated that other low-E coatingsthat may be used for coating 5 may include multiple silver based IRreflecting layers as illustrated and/or described in some of the patentsidentified above. When the coating has two silver based layers formed oncorresponding seed layers, when the UV source(s) 20 is located on thecoating side of the glass as shown in FIG. 1 then the uppermost silverlayer realizes more quality improvement than the lower silver layerbecause the seed/contact layer under the upper silver layer absorbssignificant amounts of UV before it is able to reach the seed/contactlayer under the lower silver layer; however, depending upon theintensity and duration of UV treatment both of the silver layers canrealize quality improvement because some UV will reach the lower silverlayer and the lower seed/contact layer.

One or more radiation source(s) 20 is/are provided in order to exposesubstantially the entire area of the coating 5 (as viewed from above) toUV radiation. For example, in the FIG. 1 embodiment, the source 20 maybe one or more UV lamp(s) that emit mainly UV radiation toward thecoated article and/or one or more UV lasers that emit mainly UVradiation toward the coated article. The UV may include or be radiationin the ranges of from about 300-400 nm, or from about 300-380 nm, incertain example embodiments. In certain example embodiments, thesource(s) 20 is located on the coating 5 side of the glass substrate 1so as to reduce the amount that the glass substrate 1 itself is heatedup during the exposure (e.g., the glass is not intentionally heated bythe source 20). The UV radiation 21 emitted from the sources) 20 causesthe contact/seed layer(s) 9 and/or silver based layer(s) 11 in thecoating 5 to heat up. For instance, the seed layer 9 absorbing the UVradiation and the resulting heating of the contact/seed layer 9 causesat least the adjacent silver (or gold) inclusive IR reflecting layer 11to also heat up in the exposed areas thereby physically changing atleast the silver layer 11 so as to become more dense and cause thesilver layer 11 to become more conductive and more transparent tovisible light. The UV exposure causes the coating 5 to one or both of(i) have its sheet resistance (R_(s)) drop by at least 1 ohm/sq., and/or(ii) have its visible transmission increase by at least 1%. For example,if the coating's sheet resistance is 9 ohms/square prior to the UVexposure, after the UV exposure the coating will have a sheet resistanceof no greater than 8 ohms/square.

The contact/seed layer 9 (e.g., of or including zinc oxide and/or zincstannate) may have a bandgap of from about 3.0 to 3.45 eV, morepreferably from about 3.15 to 3.45 eV, even more preferably from about3.2 to 3.4 eV, and most preferably about 3.2 eV, and because of thisbandgap the contact/seed layer 9 absorbs UV radiation 21 from the source20 (e.g., about 355 nm and/or about 308 nm) and heats up. The seed layer9 may be a semiconductor or dielectric. At least the silver in layer 11in the UV exposed area next to the heated layer 9 is in turn heated andphysically changes in the heated area(s) by densifying and becoming moreconductive (less resistance), more transparent to visible light and/ordifferently colored. Thus, the characteristics of the layer stack areintroduced as the UV is absorbed by the seed/contact layer 9 with asubsequent release of thermal energy to at least the adjacent silver (orgold) based layer 11 and possible to other layer(s) in the stack.Accordingly, the physical and optical properties of the IR reflectingsilver layer 11 are changed by the UV exposure. The exposed area willthen have a higher visible transmission and improved IR blocking.

FIG. 1 illustrates exposing the coating 5 to the UV radiation after theentire coating 5 has been deposited (e.g., sputter deposited) onsubstrate 1; however, it may be possible to instead perform the UVexposure in order to expose at least layers 9 and 11 immediately afterlayer 11 has been deposited (and/or during deposition of layer 11) butbefore layer 13 and/or 15 has been deposited. And the UV exposure may ormay not be performed in a vacuum chamber in different exampleembodiments of this invention. The monolithic coated article of FIG. 1,after being exposed as illustrated in FIG. 1 and as described above, maythen be used as a monolithic window or alternatively may be used in anIG window unit along with at least one more glass substrate as shown inFIG. 2.

FIG. 2 is a cross sectional view of a portion of an IG window unitaccording to an example embodiment of this invention, where the IGwindow unit includes the UV treated coated article made in accordancewith FIG. 1. As shown in FIG. 2, the IG window unit includes firstsubstrate 1 and second substrate 3 (e.g., both can be glass substrates)that are spaced apart from one another at least by one or moreperipheral seal(s) or spacer(s) 26. Optionally, an array of spacers (notshown) may be provided between the substrates in a viewing area of thewindow for spacing the substrates from one another as in the context ofa vacuum IG window unit. The spacer(s) 26, other spacer(s), and/orperipheral seal space the two substrates 1 and 3 apart from one anotherso that the substrates do not contact one another and so that aspace/gap 27 is defined therebetween. The space/gap 27 between thesubstrates 1, 3 may be evacuated to a pressure lower than atmospheric incertain example embodiments, and/or may be filled with a gas (e.g., Ar)in certain example embodiments. Alternatively, space 27 between thesubstrates 1, 3 need not be filled with a gas and/or need not beevacuated to a low pressure. In certain example embodiments, it ispossible to suspend foil or other radiation reflective sheet(s) (notshown) in the space. When substrate(s) 1 and/or 3 are of glass, eachglass substrate may be of the soda-lime-silica type of glass, or anyother suitable type of glass, and may be for example from about 1 to 10mm thick in certain example embodiments of this invention. The UVtreated coating 5, formed as discussed above in accordance with FIG. 1,may be formed continuously across substantially the entirety of thesupporting substrate and may be located on an interior side of substrate1 to face the gap/space 27 as shown in FIG. 2, or alternatively may belocated on the interior side of substrate 3 to face the gap/space 27.Coating 5 (e.g., low-E coating) blocks (i.e., reflects and/or absorbs)certain amounts of IR radiation and prevent the same from reaching thebuilding interior. It will be appreciated by those skilled in the artthat IR blocking/reflecting layer(s) 11 of coating 5 need not block allIR radiation, but only needs to block significant amounts thereof.

In view of the presence of IR blocking/reflecting coating (i.e., solarmanagement coating) 5, IG window units according to certain exampleembodiments of this invention as shown in FIG. 2 may have the followingsolar characteristics (e.g., where the coated glass substrate 1 is asubstantially transparent soda lime silica glass substrate from about1-6 mm thick, more preferably from about 2 to 3.2 mm thick, and theother soda lime silica glass substrate 3 is substantially transparentand from about 1-6 mm thick, more preferably from about 2 to 3.2 mmthick). In Table 1 below, R_(g)Y is visible reflection from the outsideor exterior of the window/building (i.e., from where the sun is located,and R_(f)Y is visible reflection from the interior side (e.g., fromwithin the building interior).

TABLE 1 IG Unit Solar Characteristics Characteristic General PreferredMore Preferred T_(vis) (or TY)(III. C, 2 deg.): >=50% >=60% >=68% R_(g)Y(III. C, 2 deg.):   5 to 17%   7 to 13%  9 to 11% R_(f)Y (III. C, 2deg.):   5 to 20%   7 to 14% 10 to 12% U-value: 0.10 to 0.40 0.20 to0.30 0.22 to 0.25  

It is noted that certain parameters can be tuned by adjusting layerthicknesses. For example, sheet resistance can be decreased and visibletransmission decreased by increasing the thickness of the silver basedlayer 11 and/or by providing the coating with additional silver basedlayer(s). In certain example embodiments, the coating 5 in the FIG. 1-2embodiments may have a sheet resistance (R_(s)) of no greater than 10ohms/square, more preferably no greater than 8 ohms/square, and mostpreferably no greater than 6 ohms/square.

In certain example embodiments of this invention, there is provided amethod of making a coated article for use in a window, the methodcomprising: having a coated article including a substrate that supportsa coating comprising at least one layer comprising silver locateddirectly on and contacting a layer comprising metal oxide that canabsorb ultraviolet (UV) radiation; directing UV radiation from at leastone UV source toward the coating and exposing the coating to UVradiation in order to reduce a sheet resistance of the coating and/orincrease visible transmission of the coating.

In the method of the immediately preceding paragraph, the UV source maycomprise at least one UV emitting lamp.

In the method of any of the preceding two paragraphs, the UV source maycomprise at least one UV emitting laser.

In the method of any of the preceding three paragraphs, said exposingthe coating to UV radiation may reduce the sheet resistance of thecoating by at least one ohm/square, more preferably by at least about1.5 or 2 ohms/square.

In the method of any of the preceding four paragraphs, the layercomprising metal oxide may have a bandgap of from about 3.2 to 3.4 eV.

In the method of any of the preceding five paragraphs, the layercomprising metal oxide may comprise zinc oxide.

In the method of any of the preceding six paragraphs, the layercomprising metal oxide may comprise zinc stannate.

In the method of any of the preceding seven paragraphs, the coating maybe a low-E coating.

In the method of any of the preceding eight paragraphs, the coating mayhave a sheet resistance (R_(s)) of no greater than 10 ohms/square aftersaid UV exposing.

In the method of any of the preceding nine paragraphs, said exposing thecoating to UV radiation may increase the visible transmission of thecoated article by at least 1%, more preferably by at least about 1.5 or2%.

In the method of any of the preceding ten paragraphs, the coated articlemay have a visible transmission of at least about 50% after saidexposing.

In the method of any of the preceding eleven paragraphs, the substratemay be a glass substrate.

In the method of any of the preceding twelve paragraphs, the method mayfurther comprise, after said exposing, coupling the substrate with thecoating thereon to another substrate in making an insulating glass (IG)window unit.

In the method of any of the preceding thirteen paragraphs, radiationemitted from the source may consist essentially of UV radiation.

In the method of any of the preceding fourteen paragraphs, the coatingmay further comprise a layer comprise (a) an oxide of Ni and/or Crlocated over and directly contacting the layer comprising silver, and/or(b) a dielectric layer comprising silicon nitride located over the layercomprising silver.

In the method of any of the preceding fifteen paragraphs, the source andthe coating can be located on the same side of the substrate.

As used herein, the terms “on,” “supported by,” and the like should notbe interpreted to mean that two elements are directly adjacent to oneanother unless explicitly stated. In other words, a first layer may besaid to be “on” “supported by” a second layer, even if there are one ormore layers there between.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

The invention claimed is:
 1. A method of making a coated article for usein a window, the method comprising: having a coated article including aglass substrate that supports a low-emissivity (low-E) coatingcomprising at least one layer comprising silver located directly on andcontacting a contact layer comprising zinc oxide that can absorbultraviolet (UV) radiation, the low-E coating further comprising adielectric layer between the contact layer comprising zinc oxide and theglass substrate, and an upper dielectric layer located over the layercomprising silver so that the layer comprising silver is located betweenthe upper dielectric layer and the glass substrate; directing UVradiation from at least one UV source toward the coating and exposingthe coating to UV radiation in order to reduce a sheet resistance of thecoating and/or increase visible transmission of the coating; and whereinthe coated article has a visible transmission of at least about 50%after said exposing.
 2. The method of claim 1, wherein the UV sourcecomprises at least one UV emitting lamp.
 3. The method of claim 1,wherein the UV source comprises at least one UV emitting laser.
 4. Themethod of claim 1, wherein said exposing the coating to UV radiationreduces the sheet resistance of the coating by at least one ohm/square.5. The method of claim 1, wherein the layer comprising zinc oxide has abandgap of from about 3.2 to 3.4 eV.
 6. The method of claim 1, whereinthe contact layer comprises zinc stannate.
 7. The method of claim 1,wherein the coating has a sheet resistance (R_(s)) of no greater than 10ohms/square after said UV exposing.
 8. The method of claim 1, whereinsaid exposing the coating to UV radiation increases the visibletransmission of the coated article by at least 1%.
 9. The method ofclaim 1, further comprising, after said exposing, coupling the substratewith the coating thereon to another substrate in making an insulatingglass (IG) window unit.
 10. The method of claim 1, wherein radiationemitted from the source consists essentially of UV radiation.
 11. Themethod of claim 1, where the coating further comprises a layercomprising an oxide of Ni and/or Cr located over and directly contactingthe layer comprising silver.
 12. The method of claim 1, wherein thedielectric layer and the upper dielectric layer each comprise siliconnitride.
 13. The method of claim 1, wherein the source and the coatingare located on the same side of the substrate.
 14. A method of making acoated article for use in a window, the method comprising: having acoated article including a glass substrate that supports a low-E coatingcomprising at least one substantially metallic layer comprising silverlocated directly on and contacting a contact layer comprising zinc oxidethat has a bandgap of from 3.2 to 3.4 eV, the low-E coating furthercomprising a dielectric layer between the contact layer comprising zincoxide and the glass substrate, and an upper dielectric layer locatedover the layer comprising silver so that the layer comprising silver islocated between the upper dielectric layer and the glass substrate;directing UV radiation from at least one UV source toward the coatingand exposing the coating to UV radiation in order to reduce a sheetresistance of the coating and increase visible transmission of thecoating; and wherein the coated article has a visible transmission of atleast about 50% after said exposing.
 15. The method of claim 14, whereinthe UV source comprises at least one UV emitting lamp and/or laser. 16.The method of claim 14, wherein said exposing the coating to UVradiation reduces the sheet resistance of the substantially metalliclayer by at least one ohm/square.